Floral Ontogenetic Evidence in Support of the Willdenowia Clade of South African Restionaceae

Willdenowia clade of Restionaceae was studied to understand patterns of reduction of floral elements and sample evidence for discussing the relationships of the group. All species studied are characterized by a concordant reductive trend involving the retardation/reduction of the perianth, the loss of the anterior carpel and the displacement of the remaining carpels, linked with a strongly compressed spikelet. Different modes of carpel reduction, such as a progressive or immediate loss, or fusion of two neighboring carpels, are presented and discussed. The most parsimonious event of gynoecium evolution for the Willdenowia clade is either the sterilization of two carpels in an originally trimerous gynoecium, followed by the loss of the anterior carpel, or the sudden loss of the anterior carpel, preceeding the sterilization of one lateral carpel. The concordant development of the taxa of the Willdenowia clade supports a one-time loss of a carpel and the homogeneity of the clade. Received 12 March 2001/ Accepted in revised form 29 May 2001     

Restionaceae seedlings: Morphology,anatomy and systematic implications

Restionaceae differ from most monocot families in having both epigeal and hypogeal germination. The green cotyledons associated with epigeal germination have a central vascular strand as found in most epigeal monocotyledons. In some genera the cotyledon may have a hairpin‐like structure, also described for Anthericaceae. The cotyledon of the hypogeal seedlings is short, without green pigment and largely remains embedded in the seed coat. Hypogeal germination is correlated with large, woody, indehiscent, frequently myrmecochorous nuts, while epigeal germination is found in species with smaller indehiscent nutlets or seeds, dispersed in a variety of ways. The primitive condition is most likely epigeal germination. In hypogeal seedlings of some African and Australian taxa an epicotyledonary rhizome is found between the primary root and the first leaves. Seedlings of African Restionaceae frequently have elongated culm internodes, whereas in the Australian species studied, internodes are very short, resulting in a cluster of seedling leaves. The leaf blades, which in most species are only found on the seedlings, are very simple anatomically. However, they appear to be unifacial, similar to the leaf blades of Anarthria (Anarthriaceae). The anatomical specialisations in the blades mirror those recorded for the culm anatomy. These observations are consistent with the hypothesis that Centrolepidaceae may be neotonous Restionaceae. They also corroborate the morphology of the African Restionaceae, and the presently accepted phylogeny of the African genera of Restionaceae.     

The correlation between development of atypical bisexual flowers and phylogeny in the Aroideae (Araceae)

 In the intermediate zone of the inflorescence of genera of Aroideae one can find flowers with male and female characteristics. Until now, two types of developmental sequences of atypical bisexual flowers (ABFs) have been recognized: the Philodendron type and the Cercestis type. In the Philodendron type, bisexual flowers generally consist of functional carpels and staminodes inserted on the same whorl. In the Cercestis type, the gynoecium and stamens are inserted on two different whorls. These different ontogenetic patterns represent two different pathways in the evolution of unisexual flowers in this subfamily. A molecular phylogenetic analysis of 33 genera of Araceae, based on the chloroplast trnL intron and trnL–F intergenic spacer sequences was carried out. We use this phylogenetic analysis and those published by French et al. (1995) and Mayo et al. (1997) to examine the distribution of the two types of ABFs in selected genera. Our results suggest that the two developmental patterns of ABFs in Aroideae sensu Mayo et al. (1997) do not correspond to two separate evolutionary lineages but rather are more or less consistent within clades. Although this new molecular phylogeny does not include all aroid genera, it corroborates in general, at the subfamily level, the molecular analysis of French et al. (1995) based on chloroplast DNA restriction site data and the analysis of Mayo et al. (1997) based on morphological and anatomical data. Received March 15, 2001 Accepted October 11, 2001     

Contrasting patterns of radiation in African and Australian Restionaceae

The floras of the Mediterranean-climate areas of southern Africa and southwestern Australia are remarkably species rich. Because the two areas are at similar latitudes and in similar positions on their respective continents, they have probably had similar Cenozoic climatic histories. Here we test the prediction that the evolution of the species richness in the two areas followed a similar temporal progression by comparing the rates of lineage accumulation for African and Australian Restionaceae. Restionaceae (Poales) are typical and often dominant elements in the fynbos vegetation of the Cape Floristic Region of southern Africa and the kwongan vegetation of the Southwestern Floristic Province of Western Australia. The phylogeny of the family was estimated from combined datasets for rbcL and trnL-F sequences and a large morphological dataset; these datasets are largely congruent. The monophyly of Restionaceae is supported and a basal division into an African clade (approximately 350 species) and an Australian clade (146 species) corroborated. There is also support for a futher subdivision of these two large sister-clades, but the terminal resolution within the African clade is very weak. Fossil pollen records provided a minimum age of the common ancestor of Australian and African Restionaceae as 64-71 million years ago, and this date was used to calibrate a molecular clock. A molecular clock was rejected by a likelihood ratio test; therefore, rate changes between the lineages were smoothed using nonparametric rate smoothing. The rate-corrected ages were used to construct a plot of lineages through time. During the Palaeogene the Australian lineage diversity increased consistent with the predictions of the constant birthrate model, while the African lineage diversity showed a dramatic increase in diversification rate in the Miocene. Incomplete sampling obscures the patterns in the Neogene, but extending the trends to the modern extant diversity suggests that this acceleration in the speciation rate continued in the African clade, whereas the Australian clade retained a constant diversification rate. The substantial morphological and anatomical similarity between the African and Australian Restionaceae appear to preclude morphological innovations as possible explanations for the intercontinental differences. Most likely these differences are due to the greater geographical extent and ecological variation in temperate Australia than temperate Africa, which might have provided refugia for basal Restionaceae lineages, whereas the more mountainous terrain of southern Africa might have provided the selective regimes for a more rapid, recent speciation.     

Molecular Phylogeny of Casuarinaceae Based on rbcL and matK Gene Sequences

rbcL (1310 bp) and matK (1014 bp), using 15 species representing the family. The study included analyses of Ticodendron (Ticodendraceae) and three species of Betulaceae as close relatives, and one species each of Juglandaceae and Myricaceae as outgroups. Analyses based on matK gene sequences, which provided a much better resolution than the analyses based on rbcL gene sequences alone, resulted in a single most parsimonious tree whose topology is almost identical with the strict consensus tree generated by the combined data set of rbcL and matK gene sequences. Results showed that Casuarinaceae are monophyletic, comprising four distinct genera, Allocasuarina, Casuarina, Ceuthostoma and Gymnostoma, which were not recognized until recently. Within the family, Gymnostoma is positioned at the most basal position and sister to the remainder. Within the remainder Ceuthostoma is sister to the Allocasuarina-Casuarina clade. Morphologically the basalmost position of Gymnostoma is supported by plesiomorphies such as exposed stomata in the shallow longitudinal furrows of the branchlets, a basic chromosome number x=8 and the gynoecium composed of two fertile, biovulate carpels. The three other genera, Allocasuarina, Casuarina, and Ceuthostoma, have invisible stomata in the deep longitudinal furrows of the branchlets, a higher basic chromosome number x=9 or 10–14 (unknown in Ceuthostoma), the gynoecium composed of one fertile and one sterile carpel with a single ovule (unknown in Ceuthostoma). The diversity of infructescence morphology found in the latter three genera suggests that they may have evolved in close association with the elaboration of fruit dispersal mechanisms. Received 14 September 2001/ Accepted in revised form 12 October 2001     

A molecular phylogeny and generic rearrangement of the stapelioid Ceropegieae (Apocynaceae-Asclepiadoideae)

 Representatives of nearly all genera of the taxon-rich stem-succulent stapeliads and most of the few related, leafy genera were analyzed. Sequence data from two non-coding molecular markers (ITS region of nrDNA and trnT-L and trnL-F spacers as well as the trnL intron of cpDNA) support the traditional tribal affiliation of the genera, which form a monophyletic group. This monophylum breaks into a basal Neoschumannia/Anisotoma/Riocreuxia/Sisyranthus nk;clade, from which the core Ceropegieae are derived. The four Ceropegia species included are not monophyletic, and their relationship to Brachystelma changes depending on the marker studied. The stem succulent taxa fall in a number of well supported, but unresolved clades, the most prominent being the predominantly southern African clade comprising Orbea, Stapelia and some other genera. The most derived taxa of NE Africa, Duvaliandra and White-sloanea, are basal to this southern African clade. The other clades comprise the more basal genera of stem-succulent stapeliads, including the members of the Caralluma complex. Of the 17 genera accepted by Plowes for the Caralluma complex, seven are recognized: Caralluma, Apteranthes, Australluma, Boucerosia, Caudanthera, Desmidorchis and Monolluma. New combinations are proposed in 15 cases; Caralluma adscendens var. geniculata is raised to specific rank. Anomalluma is reinstated, and Pseudolithos mccoyi is transfered to it. A broadened concept for Orbea (incl. Angolluma and Orbeopsis) is recognized, but Orbeanthus is kept separate. The monotypic Ballyanthus, recently separated from Orbea, is nested within Duvalia. Piaranthus (incl. Huerniopsis) is monophyletic. The bitypic Notechidnopsis is reduced to the type species, N. tessellata, while N. columnaris is transferred to a new genus, Richtersveldia. Received February 25, 2002; accepted June 17, 2002 Published online: November 7, 2002 Address of the authors: Dr. Ulrich Meve (e-mail: ulrich.meve@uni-bayreuth.de) and Prof. Dr. Sigrid Liede (e-mail: sigrid.liede@uni-bayreuth.de), Universit?t Bayreuth, Lehrstuhl für Pflanzensystematik, Universit?tsstrasse 30, D-95440 Bayreuth, Germany.     

The phylogeny of the austral grass subfamily Danthonioideae: Evidence from multiple data sets

The grass subfamily Danthonioideae is one of the smaller in the family. We utilize DNA sequence data from three chloroplast regions (trnL, rpoC2 and rbcL) and one nuclear region (Internal Transcribed Spacer; ITS) both singly and in combination to elucidate the relationships of the genera in the subfamily. The topology retrieved by the ITS region is not congruent with that of the plastid data, but this conflict is not strongly supported. Nine well-supported clades are retrieved by all data sets. The relationships at the base of the subfamily are clearly established, comprising a series of three clades of Merxmuellera species. The earliest diverging clade probably does not belong in Danthonioideae. The other two clades are centered in the tropical African mountains and Cape mountains respectively. A clade of predominantly North and South American Danthonia species as well as D. archboldii from New Guinea is retrieved, but the African and Asian species of Danthonia are related to African species of Merxmuellera, thus rendering Danthonia polyphyletic. The relationships of the Danthonia clade remain equivocal, as do those of the two Cortaderia clades, the Pseudopentameris and Rytidosperma clades. Paseka Mafa was tragically killed in a vehicle accident in July 2001. This paper includes information he collected during the course of his MSc in Systematics and Biodiversity Science at the University of Cape Town.     

Pollen morphology within the Monodora clade,a diverse group of five African Annonaceae genera

Pollen morphology has played a major role in elucidating infrafamiliar‐level systematics and evolution within Annonaceae, especially within the African genera. The Monodora clade is composed of five genera, Asteranthe, Hexalobus, Isolona, Monodora and Uvariastrum, which are restricted to Africa and contain together c. 50 species. A molecular phylogeny of the family showed that the monophyly of the Monodora clade is strongly supported and that it is part of a larger clade of 11 African genera. In order to support classification a detailed survey was made of the pollen morphological variation within the Monodora clade, using scanning and transmission electron microsopy. For the two most species‐rich genera, Isolona and Monodora, a molecular species‐level phylogeny was used to assess the taxonomic usefulness of the pollen characters. The survey showed a wide range of pollen morphological diversity. The most conspicuous variation concerned the occurrence of monads without a thicker outer foliation in the basal exine layer in Isolona in contrast to tetrads with a thicker outer foliation in Asteranthe, Hexalobus, Monodora and Uvariastrum. At the infrageneric level, Hexalobus, Isolona and Monodora showed the largest diversity, with various pollen types based on tectum morphology. Hexalobus is exceptional with three types within only five species. The pollen types defined in this study are hardly useful in characterizing major groups identified within both Isolona and Monodora, but they do illustrate relationships within smaller groups.     

Molecular evidence for the polyphyly of Olearia (Astereae: Asteraceae)

 Analyses of ITS sequences for 49 species of Olearia, including representatives from all currently recognised intergeneric sections, and 43 species from 23 other genera of Astereae, rooted on eight sequences from Anthemideae, provide no support for the monophyly of this large and morphologically diverse Australasian genus. Eighteen separate lineages of Olearia are recognised, including seven robust groups. Three of these groups and another eight species are placed within a primary clade incorporating representatives of Achnophora, Aster, Brachyscome, Calotis, Camptacra, Erigeron, Felicia, Grangea, Kippistia, Lagenifera, Minuria, Oritrophium, Peripleura, Podocoma, Remya, Solidago, Tetramolopium and Vittadinia. The remaining four groups and three individual species lie within a sister clade that also includes Celmisia, Chiliotrichum, Damnamenia, Pleurophyllum and Pachystegia. Relationships within each primary clade are poorly resolved. There is some congruence between this molecular estimate of the phylogeny and the distribution of types of abaxial leaf-hair, which is the basis of the present sectional classification of Olearia, but all states appear to have arisen more than once within the tribe. It is concluded that those species placed within the second primary clade should be removed from the genus, but the extent to which species placed within the first primary clade constitute a monophyletic group can only be resolved with further sequence data. Received November 12, 2001; accepted April 29, 2002 Published online: November 22, 2002 Addresses of authors: Edward W. Cross, Centre for Plant Biodiversity Research, CSIRO, GPO Box 1600, Canberra, ACT 2601, Australia (E-mail: ed.cross@csiro.au); Christopher J . Quinn, Royal Botanic Gardens, Mrs Macquaries Rd., Sydney, NSW 2000, Australia; Steven J. Wagstaff, Landcare Research, PO Box 69, Lincoln 8152, New Zealand.     

Phylogenetic position of the southern African members of the tribe Psoraleeae based on molecular and morphological data

The tribe Psoraleeae (Leguminosae subfamily Papilionoideae) comprises 185 species in nine genera that have a nearly worldwide distribution, occurring predominantly in Mediterranean regions. About 60% of the species belong to the genera, Otholobium C.H.Stirt. and Psoralea L., which have a centre of diversity in the Cape Floristic Region of South Africa. Since previous molecular studies have sampled only a few species of the tribe from this region, this study sought to determine the phylogenetic position of the southern African genera and to test whether they are monophyletic. Phylogenetic relationships were reconstructed using DNA sequence data (trnL-F, rpoB-trnC and ITS) and seven morphological characters, which diagnose the two southern African genera. The data were analysed using the parsimony method. There was strong support for the Psoraleeae as a clade, but most of the nodes within the large genera were poorly supported. The southern African species of Psoralea and Otholobium together formed a strongly supported clade. This clade was sister to the genus Hoita Rydb., but without support. However, the Psoralea species were nested within the southern African Otholobium. Additionally, some South American species that are currently recognised as Otholobium were resolved in a clade distinct from the southern African species, making Otholobium polyphyletic. Morphological characters that separate Otholobium and Psoralea are discussed. Finally, the southern African genera as currently circumscribed are not monophyletic. However, further investigations using more informative DNA loci are required to validate this observation. Furthermore, the taxonomic placement of the South American species needs to be reviewed.     

Phylogeny and divergence times of the Coluteoid clade with special reference to Colutea (Fabaceae) inferred from nrDNA ITS and two cpDNAs,matK and rpl32-trnL(UAG) sequences data

This study reconstructed the phylogeny of the Coluteoid clade using nrDNA ITS and plastid matK and rpl32-trnL_(UAG) sequences data. The analyses resolve a well-supported Coluteoid clade, as sister to Astragalus s.str. + Oxytropis, nested within the larger, strongly supported Astragalean clade. The Coluteoid clade is now composed of 12 genera including Podlechiella, Swainsona, Carmichaelia, Clianthus, Montigena, Phyllolobium, Lessertia, Sutherlandia, Sphaerophysa, Smirnowia, Eremosparton and Colutea. Within this clade, Podlechiella is the first diverging lineage followed by successive subclades of Carmichaelia + Clianthus + Swainsona, Phyllolobium, Lessertia + Sutherlandia, Sphaerophysa + Smirnowia + Eremosparton, and Colutea. We assigned the formal tribal name to this clade and redefined the tribe Coluteae. A diagnostic key to the genera of the tribe is presented. Astragalus cysticalyx and A. sinicus have no relationship with the Coluteoid clade, instead, they are nested in Astragalus s. str. Resolution within Colutea is rather low, but several smaller subclades with low to high supports are found in the genus. None of the large sections in Colutea are monophyletic. Divergence time estimates revealed that the Coluteoid clade originated in the Early Miocene (20.4 Mya). Most of its members were diverged during the Late Miocene to Pliocene. Colutea and Podlechiella form the youngest lineages where the diversification occurred in the Pliocene-Pleistocene.     

Phylogeography of Mus (Nannomys) minutoides (Rodentia,Muridae) in West Central African savannahs: singular vicariance in neighbouring populations

We studied the phylogeography of the strict savannah pygmy mice Mus (Nannomys) minutoides in West Central Africa. A total of 846 base pairs of the cytochrome b sequence were obtained for 66 individuals collected in Gabon, Cameroon, Republic of Congo and Central African Republic. These sequences were compared to those of M. minutoides from other African countries and to eight other species of the genus Mus. We performed maximum likelihood, Bayesian and nested clade analyses, as well as neutrality tests and time estimates. We show that M. minutoides is a well‐differentiated monophyletic species that separated from other pygmy mice 1.17 Myr ago. A distinct West Central African M. minutoides clade diverged early from the other African populations of the species, with a more recent common ancestor dating 0.14 Myr. West Central African populations are globally homogeneous, despite the present fragmentation of savannahs by the rain forest. However, our analyses show an unexpected vicariance between geographically close savannahs, embedded in the rain forest in Central Gabon. One of these populations is genetically more similar to very distant peripheral populations than to three closely neighbouring populations situated on both sides of the Ogooué River. A non‐river geographical barrier probably persisted in this area, durably isolating these local populations. This hypothesis about the history of the savannah landscape should be testable through the biogeographical analysis of other strict savannah small mammal species.     

Correlations between flavonoid chemistry,anatomy and geography in the restionaceae

Comparisons of the flavonoid patterns in stems and inflorescences between Australasian and South African members of the Restionaceae indicate significant differences with geography. Nine of 14 Australasian species contain gossypetin or a related 8-hydroxyflavonoid and proanthocyanidins are uncommon. By contrast, the 33 South African taxa studied contain common flavonols, flavones and glycoflavones, while proanthocyanidins are present in 29. Two anatomically related South African genera, Chondropetalum and Elegia, contain, in addition, myricetin 3-galactoside, together with the 3-galactosides of the myricetin methyl ethers, larycitrin and syringetin. These results confirm the conclusions derived from anatomy that members of Hypolaena, Leptocarpus and Restio, genera represented in both Australia and South Africa, have the distinctive flavonoids characteristic of their geographic origin rather than of their systematic position. The family as a whole is different in flavonoid pattern from other monocotyledonous families with which it is sometimes associated.     

Systematics of Amaryllidaceae based on cladistic analysis of plastid sequence data

Cladistic analyses of plastid DNA sequences rbcL and trnL-F are presented separately and combined for 48 genera of Amaryllidaceae and 29 genera of related asparagalean families. The combined analysis is the most highly resolved of the three and provides good support for the monophyly of Amaryllidaceae and indicates Agapanthaceae as its sister family. Alliaceae are in turn sister to the Amaryllidaceae/Agapanthaceae clade. The origins of the family appear to be western Gondwanaland (Africa), and infrafamilial relationships are resolved along biogeographic lines. Tribe Amaryllideae, primarily South African, is sister to the rest of Amaryllidaceae; this tribe is supported by numerous morphological synapomorphies as well. The remaining two African tribes of the family, Haemantheae and Cyrtantheae, are well supported, but their position relative to the Australasian Calostemmateae and a large clade comprising the Eurasian and American genera, is not yet clear. The Eurasian and American elements of the family are each monophyletic sister clades. Internal resolution of the Eurasian clade only partially supports currently accepted tribal concepts, and few conclusions can be drawn on the relationships of the genera based on these data. A monophyletic Lycorideae (Central and East Asian) is weakly supported. Galanthus and Leucojum (Galantheae pro parte) are supported as sister genera by the bootstrap. The American clade shows a higher degree of internal resolution. Hippeastreae (minus Griffinia and Worsleya) are well supported, and Zephyranthinae are resolved as a distinct subtribe. An Andean clade marked by a chromosome number of 2n = 46 (and derivatives thereof) is resolved with weak support. The plastid DNA phylogenies are discussed in the context of biogeography and character evolution in the family.     

Genetic and phylogenetic evidence for misidentification of Vibrio species within the Harveyi clade

Aim: This report describes the use of a six‐gene multi‐locus sequence analysis (MLSA) to correctly identify Vibrio strains of the Harveyi clade. Methods and Results: Vibrio isolates were characterized using a six housekeeping gene MLSA. The study provided evidence supporting: (i) a substantial number of reference strains maintained within commercial culture collections are misidentified taxonomically at the species level; (ii) two V. alginolyticus subclades retain species‐level divergence; and (iii) V. communis and V. owensii likely are the same species. Conclusion: A significant number (n = 10) of Harveyi clade Vibrio strains have been inaccurately identified, including evidence that V. communis and V. owensii strains, two recently discovered species assigned to the Harveyi clade, comprise a single species. Significance and Impact of the study: As Harveyi clade vibrios have an enormous impact on human and aquatic animal health, it is of paramount importance to identify members of the Harveyi clade correctly.     

CLADISTIC ANALYSIS OF PATTERNS OF ENDOTHECIAL THICKENINGS IN THE POALES/RESTIONALES

The three-dimensional structure of the endothecial thickenings in the anthers was investigated in 87 species from 70 genera, chosen to provide representative coverage of the families Cyperaceae, Restionaceae, Anarthriaceae, Ecdeiocoleaceae, Centrolepidaceae, Joinvilleaceae, Flagellariaceae, Poaceae, Xyridaceae, and Eriocaulaceae. There is complex variation in the patterns of endothecial thickening: the Eriocaulaceae, Flagellariaceae, and most Poaceae have thickenings with a complete baseplate; the Cyperaceae and most of the Restionaceae are characterized by helical thickenings; some genera in the Bambusoideae have annular thickenings; and U-shaped thickenings occur in the Xyridaceae and Eriocaulaceae and in some Poaceae and Restionaceae. Joinvillea and Ecdeiocolea have unique thickening types. Endothecial characters were subjected to cladistic analysis. Including endothecial characters in an existing cladogram of the group indicates that there is no single, well-corroborated cladogram available for the Poales/Restionales.     

An Assessment of the Systematics of Arvicanthine Rodents Using Mitochondrial DNA Sequences: Evolutionary and Biogeographical Implications

Mitochondrial DNA sequences of cytochrome b (1140-bp), 12S (375-bp) and 16S (475-bp) ribosomal RNA gene fragments were used to investigate the phylogenetic relationships of a group of African rodents referred as the arvicanthines (Family Muridae, Subfamily Murinae). A total of 49 specimens including all seven genera and 15 of the 24 arvicanthine species currently recognized as well as outgroups from the subfamily Acomyinae, Arvicolinae, Gerbillinae, Murinae and Otomyinae were examined. Our molecular data support the monophyly of the African arvicanthine genera and their partition into three distinct lineages: one composed of Arvicanthis, Mylomys and Pelomys, one composed of Desmomys and Rhabdomys, and one represented by Lemniscomys. The Indian arvicanthine Golunda is external to this clade and is part of a larger clade, together with the African arvicanthines and other African Murinae such as Aethomys, Dasymys, Grammomys, and Hybomys, for which we propose the use of the tribal name Arvicanthini. The basal relationships within this set of species are poorly resolved, suggesting the possibility of a rapid radiation. Calibration based on the fossil record suggests that this radiative event would have taken place at about 8.0 Mya (Million years ago). The identification of the Otomyinae as the sister-taxon to Arvicanthini implies that the former are true murines and should therefore be given only tribal rank within the Murinae.     

Unexpected phylogenetic relationships within the world's largest limbless skink species (Acontias plumbeus) highlight the need for a review of the taxonomic status of Acontias poecilus

Acontias plumbeus has traditionally been considered a monotypic, invariable species, a fact that highly contrasts with documented examples of high phylogenetic complexity and phenotypic diversity in other members of the Acontinae. We employed mitochondrial and nuclear DNA markers to investigate genetic structuring among A. plumbeus populations and the relationship between A. plumbeus and the closely related A. poecilus. Molecular genetic analyses revealed three clades with non‐overlapping distributions: an Eastern clade, a widely distributed Northern clade, and a Southern clade that includes topotypical A. poecilus. Morphometric analyses of preserved specimens showed that Southern clade populations are comprised of individuals with absolute and proportionally smaller body sizes than their Northern and Eastern relatives. Phylogenetic affinities within A. plumbeus indicate a complex biogeographic scenario within South Africa and suggest that A. poecilus should be considered a junior synonym of A. plumbeus instead of a truly valid species.     

Vicariance, climate change, anatomy and phylogeny of Restionaceae

Cutler suggested almost 30 years ago that there was convergent evolution between African and Australian Restionaceae in the distinctive culm anatomical features of Restionaceae. This was based on his interpretation of the homologies of the anatomical features, and these are here tested against a 'supertrec' phylogeny, based on three separate phvlogenies. The first is based on morphology and includes all genera; the other two are based on molecular sequences from the chloroplast genome-, one covers the African genera, and the other tin-Australian genera. This analysis corroborates Cutler's interpretation of convergent evolution between African and Australian Restionaceae. However, it indicates that for the Australian genera, the evolutionary pathway of the culm anatomy is much more complex than originally thought. In the most likely scenario, the ancestral Restionaceae have protective cells derived from the chlorenchyma. These persist in African Restionaceae, but are soon lost in Australian Restionaceae. Pillar cells and sclerenchyma ribs evolve early in the diversification of Australian Restionaceae, but are secondarily lost numerous times. In some of the reduction cases, the result is a very simple culm anatomy, which Cutler had interpreted as a primitively simple culm type, while in other cases it appears as if the functions of the ribs and pillars may have been taken over by a new structure, protective cells developed from epidermal, rather than chlorenchyma, cells. Cutler suggested that this convergent evolution might have been in response to Tertiary climatic deterioration, but this study finds no strong corroborating evidence for this.